Shape-stabilized phase change composite by impregnation of octadecane into mesoporous SiO

Abstract

a b s t r a c tWe developed shape-stabilized phase change composites (PCCs) for building materials with high heatstorage density by vacuum impregnation of the phase change material (PCM) octadecane into mesoporous SiO 2 . We examined the effects of the average pore size of mesoporous SiO 2 on the melting point and latent heat of the PCCs. Cyclic tests of melting and freezing were performed to evaluate leakage and degradation of the PCCs. The thermophysical properties of the PCCs were measured by differential scanning calorimetry, and the following results were obtained: (1) The impregnation ratio of the composites was above 0.95; therefore, almost all pores were completely filled with PCM. (2) The melting point of the PCMs decreased with decreasing average pore diameter, and the melting point was established as a function of average pore diameter from the Gibbs-Thomson equation, taking into account the existence of a nonfreezing layer on the surface of the pore wall. (3) The octadecane/mesoporous SiO 2 composites retained the full amount of impregnated PCM, even after cyclic heating and cooling.

Preparation and characterization of capric-myristic-stearic acid eutectic mixture/modified expanded vermiculite composite as a form-stable phase change material

“…In practice, fatty acids are impregnated into porous building materials to prepare form-stable composites. Considering the strong capillary force generated on a pore with small diameter [9], a variety of natural porous materials with smaller pores such as expanded perlite [10,11], attapulgite [12] and halloysite [13], are frequently used to avoid the leakage of fatty acids during melting process. Additionally, the low thermal conductivity of fatty acids poses a challenge for their applications.…”

Form‐stable Na 2 SO 4 ·10H 2 O‐Na 2 HPO 4 ·12H 2 O eutectic/hydrophilic fumed silica composite phase change material with low supercooling and low thermal conductivity for indoor thermal comfort improvement

“…Thereinto, Δ H m, mixture and W SiO2 were the melting enthalpy (210.0 kJ·kg −1 ) of the modified EHS and the mass fraction of SiO 2 in CPCM, respectively. As exhibited in Table , it is evident that the measured melting enthalpies (Δ H m, cpcm ) were slightly lower than the Δ H m, t , which may be attributed to the nonfreezing water layer existing as a part of the physical pore wall between EHS and SiO 2 …”

“…As exhibited in Table 3, it is evident that the measured melting enthalpies (ΔH m, cpcm ) were slightly lower than the ΔH m, t , which may be attributed to the nonfreezing water layer existing as a part of the physical pore wall between EHS and SiO 2 . 30,42,43 Besides, the supercooling degrees (ΔT) of CPCMs were also investigated, and the relevant results are also summarized in Table 3. It was obvious that the ΔT of EHS was further decreased after it was composited with SiO 2 .…”

Shape‐Stabilized Phase Change Materials Based on Stearic Acid and Mesoporous Hollow SiO2 Microspheres (SA/SiO2) for Thermal Energy Storage

“…In recent years, inorganic porous materials such as expanded graphite, expanded perlite, silica, and some polymers, which possess good sorption properties, porous structures, as well as good chemical and thermal stability, have been chosen as shape stabilization matrices. Preliminary studies of porous supports for SSPCMs show that the shape stabilization and phase change properties of SSPCMs closely depend on their average pore size . Goitandia et al demonstrated that conventional macroporous materials had the problem of serious PCM leakage .…”